Question: Reduce to lowest terms: $- \dfrac{9}{7} \div - \dfrac{9}{7} = {?}$
Explanation: Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. The reciprocal of $- \dfrac{9}{7}$ is $- \dfrac{7}{9}$ Therefore: $ - \dfrac{9}{7} \div - \dfrac{9}{7} = - \dfrac{9}{7} \times - \dfrac{7}{9} $ $ \phantom{- \dfrac{9}{7} \times - \dfrac{7}{9}} = \dfrac{-9 \times -7}{7 \times 9} $ $ \phantom{- \dfrac{9}{7} \times - \dfrac{7}{9}} = \dfrac{63}{63} $ The numerator and denominator have a common divisor of $63$, so we can simplify: $ \dfrac{63}{63} = \dfrac{63 \div 63}{63 \div 63} = 1 $